THE DEVIL, HIS MINIONS AND HIS ACTIVITIES

How you have fallen from the heavens, O morning star, son of dawn! How are you cut down to the ground, you who mowed down the nations! You said in your heart: "I will scale the heavens; above the stars of God I will set up my throne; I will take my seat on the Mount of Assembly, in the recesses of the North.  I will ascend above the tops of the clouds; I will be like the Most High!"Yet down to the nether world you go, to the rescesses of the pit! (Is 14:12-15)

Evil is not merely a lack of something but an effective agent, a living spiritual being, perverted and perverting.  A terrible reality.  Mysterious and frightening.  It is contrary to the teaching of the Bible and the church to refuse to recognize the existence of such a reality, or to regard it as a principle in itself which does not draw its origin from God like every other creature; or to explain it as a pseudo-reality, a conceptual and fanciful personification of the unknown cause of our misfortune (Pope Paul VI)

Fr. Thomas J. Euteneuer, "Exorcism and The Church Militant" page17.